1. Field of the Invention
This invention relates to a plastic cap for fixing and holding a stopper such a rubber stopper for sealing containers for medicines and, in particular, a plastic cap which is capable of assuring a high sealing property and is advantageous for the protection of the environment because of being readily subjectable to disposal of waste or incineration treatment after using the container, and a process for the production of the same and a plastic sealed container.
2. Description of the Prior Art
Containers for medicaments, in general, have been used properly as air-tight containers, closed containers and sealed containers, depending on a shape of a medicament. For a container of an injection medicament to be used in the present invention, it is obligated to use a sealed container according to General Rule 34 of the 12th Revision, Japanese Pharmacopoeia. In addition, a container for an injection medicament has such a structure as preventing it from using many times or from altering as a functional feature and in this point, it is different in quality and design from air-tight containers or closed containers for oral medicines or medicines for external application, corresponding to those to be used many times. These differences markedly appear in a sealed part and in the air-tight containers or closed containers, metallic or plastic screwed caps are generally used irrespective of whether the body of the container is of a glass or plastic considering the convenience of using many times.
For example, a container for a medicament having such a structure that a top part of an aluminum cap is separated or broken in the form of a window to expose a top part of a rubber stopper so that an injection needle can be pierced from the top part of the rubber stopper, as the container is sealed by the rubber stopper, has been proposed in Japanese Patent Laid-Open Publication Nos. 1662/1983 and 76871/1992. Furthermore, a technique comprising engaging a bonded part and separable part of a rubber stopper, in combination, and separating the separable part during use to expose the top part of the rubber stopper has been proposed in Utility Model Publication Nos. 20050/1979, 28917/1990 and 26362/1992.
In addition, Utility Model Publication No. 52853/1977 discloses a metallic cap provided with a removable synthetic resin protection cover, to be used in such a manner that a mouth of a container holding a medicament is sealed by a rubber stopper, a metallic cover provided with a window hole at a part corresponding to the central part of the rubber stopper is covered on the rubber stopper and the outside of the container mouth to tightly fix the both, the window hole is covered by the protection cover (top cover) of a synthetic resin, previously inserted in the window hole and the protection cover can readily be separated during use of the medicament.
Still further, a cap for a medicament liquid vial, having an aluminum top cover capable of being broken off by thumb has been proposed in, for example, Japanese Patent Laid-Open Publication Nos. 1662/1983 and 99969/1989, Japanese Patent Publication No. 76871/1992 and Japanese Utility Model Laid-Open Publication No. 89855/1984 and one having a top cover formed of a synthetic resin or flexible material has been proposed in Japanese Patent Laid-Open Publication No. 64961/1981 and Japanese Utility Model Laid-Open Publication No. 180556/1988.
On the other hand, in a container for an injection medicament, the prior art glass containers have been used, but when using the prior art glass containers for various new medicaments having lately been developed, there sometimes arises a problem on the quality stability of the medicaments and various efforts have been made to develop and utilize other materials such as plastics for the purpose of solving this problem. Simultaneously, great interest has been growing concerning another problem of disposal of wastes such as used containers for injection medicaments. That is, in our country and in Europe and America, regulation of the standards thereof has been proceeding as to lightening of containers for medicaments and incineration of containers for medicaments as a countermeasure for protection of the environment from contamination.
In glass containers such as glass vials, such a structure is often used that the container mouth is sealed by a rubber stopper and fastened by an aluminum cap provided with a plastic protecting cover (which will hereinafter be referred to as "aluminum cap") from the outside of the rubber stopper. In view of the whole of such a container as a system, however, separation of the system after being used needs much labor and causes workers to be exposed to danger. That is, in fact, the separation is very difficult and a radical reforming measure has been desired from workers in medical treatments, because materials for a packing container system are four kinds of glass, rubber, metal and plastic, a syringe is of a sealed container and thus has a tenacious structure and a more careful handling is required than ordinary one for treatment of medical wastes.
As described above, it has been required that not only glass containers but also rubber stoppers and aluminum caps for fastening are formed of materials excellent in burning-up property. For example, in Japanese Patent Laid-Open Publication No. 64961/1981, a cap for a glass vial, provided with a plastic protection cover, is proposed so as to simplify a step for formulation of a medicament and aluminum, etc. becomes useless. In view of the whole of such a container as a system, however, three kinds of glass, rubber and plastic are used as raw materials and a treatment after used is still complicated and difficult.
The inventors have already proposed a container for an injection medicament (of two-compartment type), made of a plastic instead of glasses, in Japanese Patent Laid-Open Publication No. 293159/1993. The container of two-compartment type is more excellent in precision of the molding dimension, as compared with glass articles of the prior art.
As described above, caps of the prior art have such a problem that since a cap body part (drum part) to be fixed in the opening part of a conatiner and a protection cover (top part) are made of different materials, separation and abandonment treatment or incineration treatment thereof after administration of a medicament is troublesome, cutting and separation or peeling of the top part and drum part in use is not smoothly effected and the state after the separation or peeling is not good. In the cap of the prior art, furthermore, there is still a problem with respect to stable storage of a medicament held in the container with maintaining the quality well for a long time. The present invention aims at providing a plastic cap with a new structure and a process for the production of the same whereby such problems can be solved. In addition, the present invention aims at lowering the production cost of such a plastic cap.
The inventors have already developed a technique for the production of an incineratable rubber stopper. Based on this technique, the present invention has been made aiming at further improving this technique and achieving a container for an injection medicament of two-compartment type, including a closing cap, with a high producibility in a step for formulation of a medicament, which container has a broad range of properly sterilizing, can readily be used at an actual medical spot and can readily be applied to various treatments after use, for example, treatments for separation, waste treatments, burning-up treatments, etc.